21699947 has 8 divisors (see below), whose sum is σ = 22704192. Its totient is φ = 20718400.

The previous prime is 21699901. The next prime is 21700001. The reversal of 21699947 is 74999612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21699947 - 2⁶ = 21699883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21699247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3704 + ... + 7557.

It is an arithmetic number, because the mean of its divisors is an integer number (2838024).

Almost surely, 2^21699947 is an apocalyptic number.

21699947 is a deficient number, since it is larger than the sum of its proper divisors (1004245).

21699947 is a wasteful number, since it uses less digits than its factorization.

21699947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11349.

The product of its digits is 244944, while the sum is 47.

The square root of 21699947 is about 4658.3201907984. The cubic root of 21699947 is about 278.9242181440.

The spelling of 21699947 in words is "twenty-one million, six hundred ninety-nine thousand, nine hundred forty-seven".